Drawing-compasses.



L. MYERS.

DRAWING COMPASSES.

APPLICATION FILED SEPT. 6,1911.

Patented Dec. 17, 1912.

\OLUMBIA ILANOGRAPH C0,, WASHINGTON. u. c.

LEOPOLD MYERS, OF BIRMINGHAM, ENGLAND.

DRAWING-COMPASSES.

Application filed September 6,, 1911.

Specification of Letters Patent.

Patented Dec. 17, 1912.

Serial No. 647,934.

To all whom it may concern Be it known that I, LnoroLD MYERS, a subject of His Majesty the King of Great Britain and Ireland, residing at Charlotte Street Steel Pen Works, Charlotte street, Birmingham, in the county of WVarwick, England, pen manufacturer, have invented new and useful Improvements in Drawing- Compasses, of which the following is a speci fication.

This invention has reference to drawing compasses of that kind which are made to fold for the pocket and consists chiefly in the improved construction and arrangement of the knee joints as hereinafter described which according to this invention are constructed with knife springs adapted to hold the lower portions of the limbs rigidly extended in a line with the upper limbs when.

in use and also to securely hold said lower limbs folded against the upper limbs when the compasses are closed for carrying in the pocket.

I will describe my invention by referring to the accompanying drawings on which' Figure 1 is a front elevation partly in section of drawing compasses constructed in accordance with this invention, this view showing the compasses open ready for use; Fig. 2 is aside elevation of the left hand leg of Fig. 1 looking toward the inside of same; Fig. 3 is a sectional plan of this leg taken on line X X of Fig. 1; Fig. 4 is a front elevation of the compasses shown in Fig. 1, but folded; F igx5 is a front elevation of one of the knife springs of the said compasses; Fig. 6 is a sectional plan through Fig. 5 taken 011 line Y Y. Fig. 7 is a-plan of the sheet steel blank from which the knife spring shown in Fig. 5 has been formed; Fig. 8 is a side elevation and Fig. 9 is a plan of the pencil socket limb of the said compasses; Fig. 10 is a side view of the said pencil socket limb; Fig. 11 is a plan of the sheet metal blank from which the pencil limb shown in Figs. 8, 9 and 10 has been formed, and Fig. 12 is a plan of the sheet metal blank for forming the point limb of said compasses.

In carrying out this invention the lower limb l of the point leg of the compasses is at the joint pin 2 (which connects this lower limb 1 to the upper limb 3) made with two flat edges marked respectively 4 and 5 and also with a fiat end 6. Fixed to the upper limb 3 of this leg there is a knife spring 7 something like the spring in the back of a pocket knife, the free end 8 of which acts against any of the flat portions 4, 5 and 6 of the lower limb 1 and will thus maintain the said lower limb turned outwardly in a line with the upper limb, as in Fig. 1, or folded back up against the same as in Fig. 4, the action of the knife spring 7 on the lower limb 1 of the leg being similar to the action of a pocket knife spring on its blade. The upper limb 3 to which the knife spring 7 is fixed is by preference although not necessarily made of a sheet metal blank bent into a U section with two ears at the top jointed on to the center joint 9 as usual and with the upper end of the lower limb 1 fitting and jointed between the two sides 10, 11 of the U between which the knife spring 7 is situated and thus the latter is practically concealed from view.

The knife spring 7 is by preference although not necessarily made of an elongated sheet steel blank such as shown in Fig. 7 which is folded along its longitudinal center line 12, the halves being pressed together so as to make the spring of double thickness of metal as shown in Fig. 5 with the folded edge 13 at the back of the spring. Thus a spring of sufficient stiffness and elasticity is formed which does not require to be hardened and tempered. The knife spring 7 fits between the two sides of the U section leg 3 and is there secured by any convenient means but preferably by the upper end of the knife spring having a recess 14 at one edge formed by the blank Fig. 7 showing two of these recesses 14 in opposite sides of the blank, so that when the spring is placed in the U section leg stout tongue like portions 15, 16 projecting from the sides of the U section leg 3 are bent and closed over into these recesses 14 thereby forcing the folded part of the spring against the back of the inside of the trough section leg and securely holding the spring in position.

The lmife spring 7 is made taper, that is, of less thickness at its outer end 8 than at its fixed end 17 and there is a certain amount of clearance at 18 between the lower end 8 of the knife spring and the underside of the lower end of the U section leg 3 to permit of the spring being forced back by the corners or heels 19 of the upper part of the lower limb 1 as it is being turned from its extended position Fig. 1 to its folded position Fig. 4 or vice versa. It is to be understood that the pencil leg 21 is fitted with a knife spring 7 to retain the pencil limb 20 in its open and closed positions similarly as above described with reference to the knife spring 7 of the leg 3 for acting on the point limb 1.

- Both the point limb 1 and the pencil limb 20 of the said compasses are by preference each made of a sheet metal blank of suitable shape about twice the width of the required limb and folded longitudinally upon itself so as to make a limb of double thickness with a nice rounded edge. The blank for forming the pencil limb is shown separately in Fig. 11 by which it will be seen that the blank has its top part 22 made with two vertical parallel side edges 5 and a fiat top part 6 at right angles thereto so that when the blank is folded along its longitudinal center line 23 the two edges 5 will come together to form the corresponding flat edge on the top part of the limb the folded side 23 forming the other flat side 4:. The portion 24 of the blank shown in Fig. 11 corre sponds with twice the width of the main portion of the limb 20 and this part 24 terminates in two inclined side wings 25, 26 which being raised to somewhat of a semicircular form in cross section form the pen cil socket when the blank is folded upon itself on its longitudinal center line 23 as in upper limbs plvo-tally attached to one an- Figs. 8, 9 and 10, the folded or rounded edge 27 of the blank being on the inside of the compasses with the divided pencil socket formed by the parts 25, 26 projecting at the proper angle to receive and hold the pencil. The sheet metal blank 28 for forming the point limb which is shown by Fig. 12 is folded upon itself upon its longitudinal center line 29 so as to make a limb of double thickness as aforesaid with a nice rounded back edge 30 and with the point 31 held in 7 position by being gripped between the two sides of the blank when closed around the same, the blank being made with two upwardly projecting square shaped cars 32 at a short distance apart which when the blank is folded as aforesaid come together face to face to form the required square shaped top of the limb and with the flat side 4 set back for some distance from the rounded edge 30 to accommodate the end 8 of the knife spring as in Fig. 1.

WVhat I claim as my invention and desire to secure by Letters Patent is 1. In a drawing compass, in combination, upper limbs pivotally connected to one another at their upper end, said limbs being of Ushaped cross section, knife springs positioned and inclosed within said U-shaped I limbs, each of said springs having its upper end fixed to its associated limb and its lower end free, and lower limbs pivoted to the lower ends of said upper limbs, said lower limbs being provided with fiat portions adapted to be engaged by said springs, whereby said lower limbs will be held in position.

2. In a drawing compass,.in combination, upper limbs pivotally connected to one another at their upper end, said limbs being of U-shaped cross section, knife springs positioned and inclosed within said Li-shaped limbs, each of said springs having its upper end fixed to its associated limb and its lower end free, and lower limbs pivoted to the lower ends of said upper limbs, said lower limbs being provided with flat portions adapted to be engaged by said springs, whereby said lower limbs will be held in position, each of said lower limbs comprising a sheet of metal folded upon itself and provided at its lower end with a socket.

3. In a drawing compass, in combination,

other at their upper ends, said limbs being of U-shaped cross section, knife springs positioned and inclosed within said U-shaped limbs, each of said springs being provided adjacent its upper end with a recess, each limb being provided with a portion bent to extend within the recess formed in the knife associated therewith to hold it in position,

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

